Human urokininogen has been characterized and appears to be a mixture of intact low molecular weight kininogen and breakdown fragments of both high and low molecular weight kininogens. Kininogen has been localized in the distal nephron of the human kidney by immunofluorescence. Kininogen appears to be present in whole human saliva. Plasma high molecular weight kininogen appears to be decreased in certain patients with hereditary angioedema and carcinoid syndrome. Both high molecular weight kininogen and prekallikrein appear to decrease in the plasma of pregnant women immediately after parturition. In both human urine and human parotid saliva, glandular kallikrein increases in normal volunteers on low salt diet or after administration of Fludrocortisone.